Electron discharge device



Oct. l5, 1946. w. E. BA'HLS Epncmou nrscHAneE vEvrcE Filed July 21. 1944 y Y xl WALTER 4ln-Tonus! Patented Oct. 15, 1946 ELECTRON DISCHARGE DEVICE Walter E. Bahls, Haddonfield,

N. J., assignor to Radio Corporation of America, a corporation of Delaware Application July 21, 1944, Serial No. 545,924 claims. (ci. 25o-27.5)

My invention relates to electron discharge devices, particularly to alternating current rectiers of the gas or vapor lled type.

An object of my invention is to provide a gas or vapor filled rectifier that is simple in construction and easy to manufacture.

A more specific object of my invention is to provide a rectier for alternating current which is reliable in operation 'nd which may be made in small sizes.

The characteristic features of my invention are defined in theappended claims and preferred embodiments thereof are described in the following specification and shown in the accompanying drawing in which Figure 1 is a longitudinal sectional view of a gas or vapor filled rectifier embodying my invention; Figure 2 is a longitudinal sectional view of another embodiment of my improved rectiiier, and Figure 3 is a detailed sectional view of still another embodiment of my improved rectier.

The particular rectifier chosen for illustrating my invention Vand shown in the drawing comprises a simple straight sided tubular glassl envelope I which can be easily formed, molded or cut from glass tubing. The lower end of the envelope is closed by a glass disc or header 2, in which is sealed parallel lead-in conductors 3 perpendicular to the header. The conductors may be arranged in a circle or in a single plane as shown. The conductors extend inwardly and through an insulating spacer 4 disposed parallel to the header. The insulating spacer is preferably round and just small enough to slide easily into the envelope. The insulating spacer shown in Figure 1 is preferably of the ceramic type and is molded with holes in registry with the lead-in conductors. This spacer member helps space the electrodes properly and connes the discharge to the space above the spacer, and also confines the ions formed to this space so that the lead-in seals are protected against ion bombardment. Rod-like anodes 5, of iron or carbon, are attached to the inner ends of two of the conductors while a coiled lament 6, which may be coated with emitting material, is attached to the inner ends of other conductors. Extensions I may be cast integrally with the spacer around the holes of the spacer through which the anodes extend to coniine the discharge to the anode tips, the distance between the inner wall of extension 'I and the surface of the anode 5 being preferably less than the mean-free-path of an electron in the gas used.

In manufacture, the header and lead-ln conductor assembly is rst made, after which the anodes may be attached to their conductors as by soldering, brazing or welding. The conductors are guided into their proper spacer holes and the spacer slid to the desired longitudinal position on the conductors. Small welded tabs 8 positioned, for example, on the under side of the spacer and attached to the anode leads and on the upper side of the spacer to the cathode` leads effectively anchor the parts together. Ceramic cement or tubular insulating members 9 surround anode leads 3 to prevent discharge between these leads and the cathode leads. The electrode assembly may then be telescoped into the envelope and the rim of the header brought into contact with the lip of the envelope and the rim and lip sealed in the usual manner. Finally the envelope may be exhausted and filled with gas and sealed oli.

In operation, a gaseous discharge passes between the cathode which becomes heated during operation by ion bombardment, and the two anodes, any material vaporized from the electrodes being effectively confined to the upper compartment of the envelope. The spacer serves the dual function of uniting the electrodes in a rigid unitary assembly, and of shielding the insulating surfaces of the envelope and header below the spacer from condensing anode and cathode materials. Leakage currents and arcing between the leads below the spacer are effectively prevented.

In Figure 2 the pant leg protection for the anodes is extended downwardly to the header. In this embodiment of my improved device, an elongated ceramic tube 9a extends from the upper surface of the header to a point just below the upper end of the anode 5. The position of lche end of the sleeve is determined by the condition ofoperation desired and could be higher or lower than that shown. Conveniently, shoulders I0 may be molded integrally with the pants leg tubes on which rests the spacer disc 4a. The spacer 4a in the embodiment s W Vin Figure 2 may be of the mica type with e` arged holes to iit over the upper end of the tubular insulators 9a. In assembly the insulator tubes 9a are dropped over the anodes, the mica disc is pressed down upon the shoulders II). Small metal tabs 8a welded to the cathode leads above the mica lock the entire assembly together. When the filament 6 is connected to its leads, the electrode and header assembly may be sealed-in in the usual manner.

In Figure 3 simplied ceramic tubing 9b is shown. Upon the upper end of the straight sided ceramic tube 9b may be placed a drawn metal thimble I I having an offset shoulder I Ic intermediate its ends to rest upon the upper end of the tube Sb and having a flange rim Ild upon which the spacer may rest. The electrodes are assembled in the same simple manner described in connection with Figure 2.

The envelope may be of the small glass type about .700 inch in diameter and now commonly used in the so-called miniature glass radio tube and commercially known as the IT4 in which the lead-in conductors may be of dumet or nickeliron-cobalt alloy about .040 inch in diameter. The cathode may comprise a coiled nickel or tungsten Wire coated with barium strontium oxides or other electron emissive coating. The diameter and cross-section of the cathode filament are proportioned in such a manner that the gas discharge will heat it and maintain it at such temperature as will produce thermionic emission. If desired, it can be made of such length that it will operate at the conventional 6.3 heater voltage if there is insuicient voltage between the cathode and anode to start with a cold cathode. Under these -conditions by applying a lament voltage for short duration the tube may be set into operation, after which the filament voltage may be removed, and the tube will continue to fuctien.

My improved rectifier is characterized by its reliaoie operation and by its simple and inexpensive construction.

While I have indicated the preferred embodiments of my invention of which I am now aware and have also indicated only one specific application for which my invention may be employed, it will be apparent that my invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations 'inay be made in the particular structure used and the purpose for which it is employed without departing from the scope of my invention as set forth in the appended claims.

What I claim as new is:

1, A rectifier comprising a tubular envelope, a flat glass disc header closing one end of said envelope, a disc-shaped insulating spacer in andY disposed across the envelope parallel to said header, parallel lead-in conductors sealed perpendicularly through said header and extending through said insulating spacer, metal tabs welded to said conductors to prevent movement of said spacer along said conductors, a cathode mounted on the inner ends of two of said conductors, a rod-like anode mounted on the inner end of another of said conductors, an insulating element surrounding said anode, the anode and cathode electrodes being in operative relationship on one side of said spacer and separated from said header by said spacer.

2. A rectifier comprising a tubular envelope closed at one end with a^` glass disc type header, parallel lead-in condudtfirs sealed through said header, a cathode mounted on the inner ends of two of said conductors and rod-like anodes mounted on the ends of the other of said conductors, a ceramic tube telescoped over said anodes and their leads and extending from said header to points below the upper ends of said anodes, means holding said tubes against said header and bracing said conductors comprising an insulating disc extending across the envelope parallel to the header below the upper ends of said tubes and having openings to embrace the ceramic tubes and cathode conductors.

3. A rectiiier comprising an envelope closed at its lower end with a glass disc header, a plurality of parallel lead-in conductors sealed in said header, ceramic tubes telescoped over two of said conductors, rod-like anodes attached to the inner ends oi said two conductors, a iilamentary cathode attached to the inner ends of twov other of said conductors, a drawn metal thimble fitted over the upper end of said tubes, said thimble having shoulders to support the thimbles on the upper ends of the tubes, the lower rims of the thimbles having outwardly directed flanges, an insulating disc parallel to said header resting upon said flanges and metal tabs on the cathode conductors holding said disc upon said ianges.

4. A rectiiier including an envelope having a press, a plurality of conducting means extending through and sealed in said press, a rod-like anode supported on the inner end of one of said conducting means, and a lamentary cathode supportedv by other conducting means, and a transverse insulating element extending across the envelope below the inner end of said anode and said cathode and shielding said ypress from said cathode and said anode, and insulating means surrounding said anode and extending between said press and the inner end of said anode and terminating below the end of said anode and spaced from the end of said anode.

5. An electron discharge device including an r' elongated envelope closed at one end by a press,

a plurality of lead-in conducting means extending through said press, a plurality of rod-like anodes supported within said envelope and a cathode supported within said envelope from said lead-in conducting means, tubular elements of insulating material surrounding said anodes and their respective conducting means and extending between the press and the inner ends of said anodes, and supporting means on said insulating tubular elements and a transverse insulating member supported on said supporting means and means securing said transverse insulating member against the supporting means on said tubular elements.

WALTER E. BAHLS. 

